We are pouring greenhouse gases into the atmosphere with potentially devastating consequences.

Scientists calculate that we need to stabilize the concentration of carbon dioxide in the atmosphere at no more than 350 parts per million (ppm) to prevent runaway global warming. We are already at 390 ppm, and adding to this at roughly 2 ppm a year. In other words, we not only have to halt the increase of global carbon emissions, we have to turn the process around, and fast. We have to reduce global carbon emissions by 80 percent or more.

It's also clear that there is a lot we can do. When we look at the major sources of carbon emissions and where the efforts are currently directed, there is one area where we have barely scratched the surface: our buildings.

Forty percent of total energy consumption and greenhouse gas emissions in the United States can be attributed to operating buildings — heating them, cooling them, lighting them and providing hot water. The emissions are most intense in cities. Buildings are responsible for almost 80 percent of New York's carbon footprint. For Hong Kong, the figure is over 70 percent, and for London, 52 percent. To put this in perspective, SUVs account for just 3 percent of emissions in North America.

If we are to successfully tackle global warming, it's clear we have to do something about the carbon footprint of our buildings. Over 90 percent of buildings in most cities are old, and most of them will still exist in 2050. It is this aging, energy-inefficient residential and office stock that we need to tackle.

So the bad news is that we need to refurbish entire cities. The good news is that if we do, we will gain far more than just climate change benefits.
>>>